Shoulder Impingement

The shoulder is the most complex joint in the body. It is capable of moving in more than 16,000 positions. Many of its ailments, including the most common ones, involve biomechanical mechanisms that are unique to the shoulder. The most common shoulder problem for which professional help is sought out for is shoulder impingement (Haig 1996). Shoulder impingement is primarily an overuse injury that involves a mechanical compression of the supraspinatus tendon, subacromial bursa, and the long head of the biceps tendon, all of which are located under the coracoacromial arch (Prentice 2001). Impingement has been described as a continuum during which repetitive compression eventually leads to irritation and inflammation that progresses to fibrosis and eventually to rupture of the rotator cuff. Because impingement involves a spectrum of lesions of tissue in the shoulder, a working knowledge of its structural relationships will facilitate an understanding of the factors that result in abnormalities. This paper will provide knowledge of the anatomy, biomechanics, and correct rehabilitation involved with shoulder impingement.

Impingement syndrome was originally described by Dr. Charles Neer as mechanical impingement of the supraspinatus muscle and the long head of the biceps tendon underneath the acromial arch. Neer classified three stages of impingement. Stage I is characterized by edema and hemorrhage of the rotator cuff and suprahumeral tissue. Stage II is characterized by fibrosis of the glenohumeral capsule and subacromial bursa and tendonitis of the involved tendons. Patients usually demonstrate a loss of active and passive range of motion because of capsular fibrosis. Stage III is the most difficult to treat and is characterized by disruption of the rotator cuff tendons. This includes rotator cuff tears, biceps rupture, and bone changes. Since this is a continuous disease process, there is often overlap of signs and symptoms (Hawkins and Abrams 1987).

For descriptive purposes, factors related to shoulder impingement can be divided into intrinsic and extrinsic categories. Intrinsic factors directly involve the subacromial space and include changes in vascularity of the rotator cuff, degeneration, and anatomy or bony anomalies. Extrinsic factors include muscle imbalances and motor control problems of the rotator cuff and parascapular muscles, functional arc of movement, postural changes, training errors, and occupational or environmental hazards. More likely, the cause of impingement has multiple factors. However, all factors may be important and the key factor in any case depends on individual circumstances.

According to Neer, the anterioinferior one third of the acromion is thought to be the causative factor in mechanical wear of the rotator cuff through a process called impingement (Donatelli 2004). Neer believes that the supraspinatus and long head of the biceps are subjected to repeated compression when the arm is raised in forward flexion. The result of repeated forward flexion is that the suprahumeral tissue is effectively driven directly under the anterioinferior one third of the acromion.

A force couple is defined as two forces of equal magnitude, but in opposite direction that produce rotation on a body. Two primary force couples are used in the shoulder to control the scapula and humerus. The scapular force couple is formed by the upper fibers of the trapezius, levator scapulae, and the upper fibers of the serratus anterior. The lower portion of the force couple is formed by the lower fibers of the trapezius and lower fibers of the serratus anterior. Simultaneous contraction of these muscles produces a smooth rhythmic motion to rotate and protract the scapula along the posterior thorax during elevation of the arm (Donatelli 2004). The scapular muscles function to rhythmically position the glenoid relative to the humeral head, therefore maintaining a normal length-tension relationship with the rotator cuff...

...dislocation after a severe trauma is a glenohumeral dislocation.
Overhead sports such as tennis, volleyball, and baseball are associated with glenohumeral
instability. (2) These activities cause the joint to be in abduction and external rotation.
Repetition of motion, collision, or falling on an outstretched arm can lead to instability
and/or dislocation. The Glenohumeral joint is already prone to dislocation, because of it
being a large head of the humerus going into a relatively small socket. Almost ninety five
percent of dislocations in the glenohumeral joint are anterior.(2)
Anatomy
The shoulders dynamic joint components provide the shoulder with the stability. The muscles and tendons form a cuff like arrangement around the joint.(2) The glenohumeral joint relies on support from a group of four muscles know as the rotator cuff. These muscles allow the shoulder to function, while maintaining balance between mobility and stability.(3) The rotator cuff allows the humeral head to stay within 1-2 millimeters of the middle of the glenoid fossa.(3) These muscles compress and depress the humeral head to prevent it from rolling off the top of the fossa.(3) More Specifically, the Supraspinatus works closely with the deltoid for arm flexion and abduction. The Supraspinatus comes from the Supraspinatus fossa of the scapula, and attaches to the greater tuberosity of the humeral head .(3)The subscapularis, is an...

...ShoulderImpingement
Just like the hip our shoulder is one of the most used joints in our body. When you think about how much our shoulders do on an everyday basis just the wear and tear alone, you can see why shoulder injuries are common. The glenohumeral joint is a very complex joint; it has more range of motion than any other joint which is not always a good thing if the joint is not stable. The muscles of this joint are required to stabilize the joint as well a work together to help in raising the arms. Like any other joint if one muscle is weak it can throw off the whole complex and make the joint not work properly also causing other muscles to work harder and possibly over compensate for the lack of the work the hurt muscle is doing. One of the many injuries that can occur in the shoulder joint is called an impingement. A shoulderimpingement involves a compression of soft tissues between the head of the humerus and the underside of the acromin process or coracoacromial ligament. An impingement can be caused by two different things but in many different way, the first way is purely structural and the second way is repetitive motions especially those involving motions that are above the head for a long period of time or the same over head motion. Impingements can be anything from just inflammation to bursitis even...

...The Shoulder Joint
The glenohumeral joint, or as it is more commonly referred to the shoulder joint , is one of the most flexible and unstable joints in the body. As a ball and socket joint the shoulder allows circular motion and hinge movement. The rounded head or ‘ball’ of the humerus rests in the shallow dish shaped cavity or ‘socket’ created by the glenoid fossa of the scapula. This allows for a wide range of motion around several axes.
There are two main bones that make up the shoulder joint, the humerus and the scapula. The ball of the humerus is stabilized and cushioned by cartilage around the glenoid fossa socket. Ligaments connect the bones together and tendons then connect those bones to surrounding muscles. For example, the bicep tendon attaches to the biceps muscle to the shoulder to stabilize the joint and the muscles and tendons in the rotator cuff also play an important role in supporting the shoulder joint. The shoulder joint is held in place by the rotator cuff muscles.
These four muscles are: supraspinatus, infraspinatus, teres major, and subscapularis. All four are share the same insertion point on the greater tubercle of the humerus. Injury to any of these four muscles results in severe damage, restricted movement, and pain to all the others. Pitchers in baseball, swimmers, tennis players, and boxers commonly tear their rotator cuff muscles from...

...Osteopathic Clinical Practice and Research 1
SHOULDERIMPINGEMENT SYNDROME: THE EFFECT ON SERRATUS ANTERIOR, UPPER TRAPEZIUS AND DELTOID DURING SHOULDER ABDUCTION
BY ANDREW MCLEOD
PROJECT SUPERVISORS: DR SANDRA GRACE AND DR ZAC CROWLEY
INTRODUCTION
Shoulderimpingement is one of the most common conditions affecting the shoulder. According to Neer (1972), shoulderimpingement accounts for between 44-65% of all cases of shoulder pain. Whilst its occurrence is common, shoulderimpingement is also commonly misunderstood and difficult to diagnose (Cools et al., 2003). The term ‘shoulder’ will be described in detail in the anatomy section of the body of this paper. In short, it refers to the shoulder joint complex, which comprises three separate joints, being the scapulothoracic, acromioclavicular and glenohumeral joints and their respective skeletal, ligamentous, muscular, vascular and nervous components. The term ‘impingement’ in the context of the shoulder usually refers to compression and mechanical abrasion of various components of the shoulder during certain types of movement, such as elevation (Neer, 1972). This, however, is not the only meaning of impingement....

...How can a lack of dorsiflexion lead to shoulder pain in a person who plays volleyball?
I am going to start by imagining a student who would walk into my tennis club for a lesson. This student would tell me about a shoulder discomfort that surfaces especially when performing overhead motions. I would then find out that she has been a volleyball player for quite some time. During my evaluation, which would include walking and light running, I would notice poor ankle dorsiflexion (maybe due to an ankle sprain). I would then continue to use my observation skills to trace out a path of the injury from the foot to the shoulder. The first thing I noticed is a shoe scrape (Hoppenfeld, 142). This occurred because the athlete had a loss of ankle dorsiflexion which is an upward foot movement produced by the activity of the front part of the shin muscles. According to Dr. Romanov, "the front part of the foot would be higher than the rear part in relation to the horizontal plane." The dorsiflexion action is not a lift of the toes, but rather a lifting of the front part of the foot. The plantar flexion action has to be done in such a manner that it applies maximum force against the ground in the shortest possible time. The more time the person spends on the ground applying force, the longer it takes. This student for instance, scraped the toe of the shoe during gait. The student also flexed her hip excessively during gait. I believe that...

...The Shoulder Joint.The Shoulder is an enarthrodial or ball-and-socket joint. The bones entering into its formation, are the large globular head of the humerus, received into the shallow glenoid cavity of the scapula, an arrangement which permits of very considerable movement, whilst the joint itself is protected against displacement by the strong ligaments and tendons which surround it, and above by an arched vault, formed by the under surface of the coracoid and acromion processes, and the coraco-acromial ligament. The articular surfaces are covered by a layer of cartilage : that on the head of the humerus is thicker at the centre than at the circumference, the reverse being observed in the glenoid cavity. The ligaments of the shoulder are, the Capsular. Coraco-humeral.Glenoid.* The Capsular Ligament completely encircles the articulation ; being attached, above, to the circumference of the glenoid cavity beyond the glenoid ligament; below, to the anatomical neck of the humerus, approaching nearer to the articular cartilage above, than in the rest of its extent. It is thicker above than below, remarkably loose and lax, and much larger and longer than is necessary to keep the bones in contact, allowing them to be separated from each other more than an inch, an evident provision for that extreme freedom of movement which is peculiar to this articulation. Its external surface is strengthened, above, by the Supraspinatus ; above and...

...it appear to be normal.
Is still unknown causes but most researcher agree that:
Abnormalities in cytokines function
Increase substance P in spinal cord
Decrease blood flow to thalamus
Illness or injury causing trauma to body
Abnormal sensory processing in CNS
Combination of medication, physical theraphy and self-help strategies
Nutrition
gentle exercise and stretching-helps maintain muscle tone and reduces pain and stiffness.
Meditate
Non-narcotic pain relievers (e.g. tramadol)
low doses of antidepressants – help improve sleep and relieve pain
SHOULDER JOINT
INTRODUCTION
it is a type of synovial joint (ball and socket)
it is freely moveable, nearly in all directions
it is unstable joint (easily dislocate), as the head of humerus articulate with glenoid cavity of scapula a bit shallow, so, it is compensated by rotator cuff muscles, tendons, ligaments, and the glenoid labrum.
BONE OF SHOULDER JOINT
1) Clavicle
2) Scapula
3) Humerus
BONE
CLAVICLE
SCAPULA
HUMERUS
FEATURE
It is the only long bone in the body which lies nearly horizontal, with NO medullary cavity and ossify in membrane
Has a shaft with 2 end (acromial /lateral end and sternal/medial end)
Flat, triangular bone which lies on posterior wall of thorax, between 2nd to 7th ribs
The scapula has 3 processes:
Spinous process
Acromion process
Corocoid process
The glenoid cavity The glenoid cavity is an irregularly shaped oval. It...